1. Field of the Invention
The present invention relates to data communication via power lines. More specifically, it relates to a system of sending signals down the existing power lines to operate such devices as remote controls for VCR's, personal computers, security systems, and the like. The possible uses for this invention are endless and it is therefore hard to pinpoint exactly what fields of human endeavor stand to benefit most from the invention. Certainly the field of medicine stands to reap substantial benefits because of the increased possibilities of transmission of digitized computer medical information. Remote areas, served by electrical power lines but not having telephone lines, may now access all sorts of digital information resources previously unavailable. Marketing and service information for all sorts of products will gain an instant increase in the number of potential buyers by the use of this invention.
Thus it can be seen that the potential fields of use for this invention are myriad, and the particular preferred embodiment described herein is in no way meant to be limiting the particular field chosen for exposition of the details of the invention.
2. Description of the Prior Art
In the past, it has been attempted to provide telephone communications to rural areas, not served by telephone lines. Power lines that were widely installed with the assistance of the Rural Electrification Administration of the United States government were commonly used. These known devices, although they were broadly means for providing communication over a power line grid, were strictly analog in nature. They were not particularly successful because of the inherent limitations of the analog bandwidth and their focus on the transmission of voice signals only. The main drawback was that only one call could be handled at a time.
Eventually, nearly all households and businesses in this country became wired with telephone circuitry. Over the years the introduction of digital computers and the corresponding introduction of digital communications took advantage of the nearly universal telephone hookups in this country. Almost all the equipment designed for digital communication was designed to use the existing telephone lines. The lowly electrical power line was forgotten as to its potential for carrying information communication as well as power.
As the world moves to a more global economy, there now exist many third world countries with electric power lines but having sparse, or none at all, telephone wiring. The need therefore exists, much as in the early rural United States, for a device providing communications ability to the common electrical power line. Today, however, "communications ability" means much more than the early voice communication envisioned by the early patents. It means control of the operation of all sorts of electrical appliances as well as the transmission, reception, and storage of vast amounts of textual and graphical information. To my knowledge, there has not, until now, been an attempt to apply sophisticated communications technology to an existing electrical power line grid. As will be seen, the simplicity and effectiveness of my invention is not rivaled in the prior art.
The following pertinent prior art was discovered in a search conducted at the United States Patent and Trademark Office:
U.S. Pat. No. 5,051,720, issued to Kittirutsunetorn on Sep. 24, 1991, shows a remote control system using the power line of a remote site. This patent indicates many of the communications abilities envisioned by the instant invention. The patented system of controlling power at a remote site includes a two channel modem having a first channel dedicated for transmitting power controlling messages to power control modules and a second channel dedicated to transmitting data messages to computerized equipment. The power control modules include a master control module which is plugged into a power line extending through the remote site and one or more slave modules also coupled to the remote site power line for receiving therethrough power control signals transmitted by the master control unit. A user, located at a site distant from the remote site, may turn power on, off, or dim the power to any of a plurality of appliances which are coupled to the remote power line by way of slave power control units.
Insofar as the patent shows control of several sorts of equipment through an existing household power line, U.S. Pat. No. 5,051,720 is hereby incorporated by reference into the instant disclosure. The patent teaches how one may control computers, printers, alarm systems, telephone answering machines, lighting, video recorders, magnetic tape recording machines and other remote appliances simply by plugging them in to a power line circuit at a given site. The patent does not use the existing power line or power line grid between the local and remote site to transmit the control signals.
By contrast, the device of the instant invention uses the main electrical power lines for transmission of the control signals to the various controlled equipment. There is no need to use a conventional telephone line for the operation of this invention. The instant invention proposes transmitting coded signals over a line similar to the telephone line used by the above patent and others. However, a major difference is that the transmission is not dependent on the existence of any telephone line or any other sort of link such as radio or microwave.
U.S. Pat. No. 2,264,395, issued to Mitchell on Dec. 2, 1941, shows a power line carrier frequency telephone system. The patent shows a line for transmitting electric power, for example, of relatively high voltage and low frequency between two or more points and to a plurality of power consumers, some or all of whom, together with others in the locality through which the line extends, desire telephone service. Telephone subscribers stations are coupled to the power line and are adapted to receive and transmit telephone signals on high frequency or carrier waves. At each station and at the central office for the system, means are provided for modulating the carrier waves for transmission outgoing from the station or office, and for demodulating a modulated carrier wave incoming to the station or office. A single source of carrier wave, common to the system, is located at the central office, or at one of the stations, or may be coupled to the power line at some point along the line outside of a station or the central office. Because the distances between stations and between a station and the central office may be appreciable and will vary with the stations involved in a particular call, there may be phase differences between the carrier wave at the called or calling station and that of the calling or called station. That is to say, there may be phase differences in transmission occurring between the carrier wave employed for modulation and the carrier wave employed for demodulation. Any adverse effect, i.e., loss in demodulation output at the receiving station, that might follow from such a condition may be precluded by arranging the stations and the central office to transmit and receive only the carrier wave and one side-band of the modulated carrier wave. When a pair of stations are using the telephone capabilities of the patented system, other users are essentially blocked from access to prevent potential interference. To the extent that the patent teaches transmission of analog signals by superposition of high frequency carrier waves upon normal power lines, U.S. Pat. No. 2,264,395 is hereby incorporated by reference.
By contrast, the device of the instant invention is intended to transmit coded digital signals over existing electric power lines. The above mentioned problems of phase difference and potential interference are circumvented. By using existing high speed digital packet transfer technology and unique coding for individual users it is anticipated the instant invention will be accessible to many simultaneous users on the same electrical power grid.
U.S. Pat. No. 2,264,396, issued to Moore on Dec. 2, 1941, shows a device similar to that discussed above with respect to the patent to Mitchell. A different modulator-demodulator circuit is shown in the patent to Moore. When a pair of stations are using the telephone capabilities of the patented system, other users are essentially blocked from access to prevent potential interference. To the extent that the patent teaches transmission of analog signals by superposition of high frequency carrier waves upon normal power lines, U.S. Pat. No. 2,264,396 is hereby incorporated by reference.
By contrast, the device of the instant invention is intended to transmit coded digital signals over existing electric power lines. The above mentioned problems of phase difference and potential interference are circumvented. By using existing high speed digital packet transfer technology and unique coding for individual users it is anticipated the instant invention will be accessible to many simultaneous users on the same electrical power grid.
U.S. Pat. No. 2,032,360, issued to Green on Mar. 3, 1936, shows a power line carrier system. The patented device shows the use of current transformers allowing impedance matching of the overall network. To the extent that the patent teaches transmission of analog signals by superposition of high frequency carrier waves upon normal power lines, U.S. Pat. No. 2,032,360 is hereby incorporated by reference.
By contrast, the device of the instant invention is intended to transmit coded digital signals over existing electric power lines. The above mentioned problems of phase difference and potential interference are circumvented. By using existing high speed digital packet transfer technology and unique coding for individual users it is anticipated the instant invention will be accessible to many simultaneous users on the same electrical power grid.
It will be noted that all the prior art devices require either a telephone line for the transmission of digital signals or abandon digital signals entirely in favor of frequency modulated signals if they use an electrical power line.
None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed.